scholarly journals Photonics-Assisted Terahertz-Wave Beam Steering and Its Application in Secured Wireless Communication

Photonics ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 9
Author(s):  
Kazutoshi Kato
Keyword(s):  
Wireless Communication ◽  
Power Efficiency ◽  
Electromagnetic Waves ◽  
High Speed ◽  
Phased Array ◽  
Beam Steering ◽  
Terahertz Wave ◽  
Coherent Detection ◽  
Terahertz Waves ◽  
Optical Domain

Beam forming and beam steering are inevitable technologies for the practical application of high-frequency electromagnetic waves. Specifically, beam control technology using a phased array for terahertz waves above 100 GHz is necessary to realize the future of high-speed wireless communication. By photomixing, which is a promising method for generating terahertz waves, the phase of the generated waves can be tuned in the optical domain, so that the beam from the phased array can be controlled by photonics technologies. Directing the beam of a terahertz wave enables wireless communication to be improved not only via an increase in power efficiency but also in security in the physical layer of the wireless transmission. By utilizing this advantage and using coherent detection at the receiver, a secured wireless communication system is proposed, and the fundamental mechanism is demonstrated in a feasibility experiment.

scholarly journals Terahertz Beam Steering Concept Based on a MEMS-Reconfigurable Reflection Grating

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2874
Author(s):  
Xuan Liu ◽  
Lisa Samfaß ◽  
Kevin Kolpatzeck ◽  
Lars Häring ◽  
Jan C. Balzer ◽  
...  
Keyword(s):  
Diffraction Grating ◽  
High Speed ◽  
Beam Steering ◽  
Vertical Displacement ◽  
Grating Period ◽  
Terahertz Waves ◽  
Large Area ◽  
Electrostatic Actuators ◽  
Reflection Gratings ◽  
Reflection Grating

With an increasing number of applications of terahertz systems in industrial fields and communications, terahertz beamforming and beam steering techniques are required for high-speed, large-area scanning. As a promising means for beam steering, micro-electro-mechanical system (MEMS)-based reflection gratings have been successfully implemented for terahertz beam control. So far, the diffraction grating efficiency is relatively low due to the limited vertical displacement range of the reflectors. In this paper, we propose a design for a reconfigurable MEMS-based reflection grating consisting of multiple subwavelength reflectors which are driven by 5-bit, high-throw electrostatic actuators. We vary the number of the reflectors per grating period and configure the throw of individual reflectors so that the reflection grating is shaped as a blazed grating to steer the terahertz beam with maximum diffraction grating efficiency. Furthermore, we provide a mathematical model for calculating the radiation pattern of the terahertz wave reflected by general reflection gratings consisting of subwavelength reflectors. The calculated and simulated radiation patterns of the designed grating show that we can steer the angle of the terahertz waves in a range of up to ± 56.4 ∘ with a maximum sidelobe level of −10 dB at frequencies from 0.3 THz to 1 THz.

scholarly journals Nonlinear terahertz effects of gold nanofilms

2021 ◽  
Vol 14 (1) ◽  
pp. 20-30
Author(s):  
Peidi Yang ◽  
Baolong Zhang ◽  
Jinglong Ma ◽  
Yutong Li ◽  
Jungang Miao ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
High Speed ◽  
Strong Field ◽  
Nonlinear Behavior ◽  
Nonlinear Effects ◽  
Tunneling Effect ◽  
High Resistivity ◽  
New Paradigm ◽  
Terahertz Waves ◽  
Hybrid Substrates

Nonlinear interaction between strong-field terahertz electromagnetic waves and matters will become one of the next hot research frontiers in nonlinear optics. However, the lack of strong terahertz radiation sources and appropriate nonlinear terahertz materials have impeded its progress. Here we systematically have investigated the strong-field terahertz nonlinear effects of gold (Au) nanofilms on different substrates, including SiO2, high-resistivity Si and SiO2-high-resistivity Si hybrid substrates. The strong-field terahertz waves are emitted from lithium niobate crystals via tilted pulse front technique, and obvious nonlinear transmission responses are observed along with varying the incident field strengths for all the Au samples on the three types of the substrates. The nonlinear behavior is enhanced when the gold nanofilm thickness increases, which can be qualitatively understood by introducing the quantum tunneling effect and carrier multiplication theory generated at the Au nano-slits under the illumination of the strong-field terahertz pulses. Our demonstrations not only open a new paradigm for nonlinear terahertz investigations and future high-speed terahertz devices, but also provide an effective platform for exploring extreme terahertz sciences.

scholarly journals Metamaterial-Based Reconfigurable Intelligent Surface: 3-D Meta-Atoms Controlled by Graphene Structures

2021 ◽  
Author(s):  
Carlos Molero ◽  
Ángel Palomares-Caballero ◽  
Antonio Alex-Amor ◽  
Ignacio Parellada-Serrano ◽  
Francisco Gamiz ◽  
...  
Keyword(s):  
Wireless Communication ◽  
Communication Systems ◽  
Electromagnetic Waves ◽  
High Speed ◽  
Electromagnetic Response ◽  
Wireless Communication Systems ◽  
Full Wave ◽  
Communication Paradigm ◽  
Wireless Environment ◽  
Meta Atom

The upcoming high-speed wireless communication systems will be hosted by millimeter and sub-millimeter-wave frequency bands. At these frequencies, electromagnetic waves suffer from severe propagation losses and non-line-of-sight (NLOS) scenarios. A new wireless communication paradigm has arrived to resolve this situation through the use of reconfigurable intelligent surfaces (RIS). These metadevices are designed to reconfigure the wireless environment in a smart way. Traditional RIS designs based on the implementation of 2-D configurations have been considered up to now. However, 3-D structures enable an extra degree of freedom in the design that can be taken as an advantage for the development of improved RIS structures with advanced functionalities. This article proposes the implementation of a novel electronically-reconfigurable RIS based on the use of 3-D graphene meta-atoms. The reconfigurability lies on the graphene conductivity, easily tunable with a biasing voltage. Different conductivity values vary the meta-atom electromagnetic response, modifying the RIS functionality. A multi-objective optimization framework determines the optimal phase state of each meta-atom to accomplish the desired RIS performance. The operation of the RIS as an efficient beam steerer/splitter, absorber and polarization selector is validated with full-wave results.

scholarly journals Frequency Diverse Array Antennas: From Their Origin to Their Application in Wireless Communication Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Shaddrack Yaw Nusenu ◽  
Abdul Basit
Keyword(s):  
Wireless Communication ◽  
Communication Technology ◽  
Communication Systems ◽  
Phased Array ◽  
Beam Steering ◽  
Array Antenna ◽  
Wireless Communication Systems ◽  
Phased Array Antenna ◽  
Frequency Diverse Array ◽  
Near Future

Wireless communication systems have gained considerable growth rate nowadays, with the anticipation that communications will be available everywhere and anywhere in the near future. Phased array antenna whose beam steering is fixed in an angle for all range cells has been utilized for wireless communications. To mitigate this problem, a new array concept, namely, frequency diverse array (FDA), was proposed. This paper presents how FDA technology could be useful in today’s wireless communication technology. FDA is distinct from phased array in a sense that it employs frequency increment across array elements. The use of a frequency increment creates a beam steering that is a function of angle, time, and range which allows the FDA antenna to transmit the energy along the prespecified range and angle direction. In addition, we consider the time-variant beampattern aspect of an FDA, which has normally been ignored in the literature. In this study, we present the mathematical fundamentals of FDA antenna and why it could be exploited for wireless communication systems. Furthermore, FDA using Butler matrix for communication has been discussed. Performance analysis in terms of transmit beampattern, signal-to-interference-and-noise ratio (SINR), and direction of arrival has been presented and compared with that of phased array antenna.

scholarly journals Metamaterial-Based Reconfigurable Intelligent Surface: 3-D Meta-Atoms Controlled by Graphene Structures

2021 ◽  
Author(s):  
Carlos Molero ◽  
Ángel Palomares-Caballero ◽  
Antonio Alex-Amor ◽  
Ignacio Parellada-Serrano ◽  
Francisco Gamiz ◽  
...  
Keyword(s):  
Wireless Communication ◽  
Communication Systems ◽  
Electromagnetic Waves ◽  
High Speed ◽  
Electromagnetic Response ◽  
Wireless Communication Systems ◽  
Full Wave ◽  
Communication Paradigm ◽  
Wireless Environment ◽  
Meta Atom

The upcoming high-speed wireless communication systems will be hosted by millimeter and sub-millimeter-wave frequency bands. At these frequencies, electromagnetic waves suffer from severe propagation losses and non-line-of-sight (NLOS) scenarios. A new wireless communication paradigm has arrived to resolve this situation through the use of reconfigurable intelligent surfaces (RIS). These metadevices are designed to reconfigure the wireless environment in a smart way. Traditional RIS designs based on the implementation of 2-D configurations have been considered up to now. However, 3-D structures enable an extra degree of freedom in the design that can be taken as an advantage for the development of improved RIS structures with advanced functionalities. This article proposes the implementation of a novel electronically-reconfigurable RIS based on the use of 3-D graphene meta-atoms. The reconfigurability lies on the graphene conductivity, easily tunable with a biasing voltage. Different conductivity values vary the meta-atom electromagnetic response, modifying the RIS functionality. A multi-objective optimization framework determines the optimal phase state of each meta-atom to accomplish the desired RIS performance. The operation of the RIS as an efficient beam steerer/splitter, absorber and polarization selector is validated with full-wave results.

scholarly journals Metamaterial-Based Reconfigurable Intelligent Surface: 3-D Meta-Atoms Controlled by Graphene Structures

2021 ◽  
Author(s):  
Ángel Palomares-Caballero ◽  
Carlos Molero ◽  
Antonio Alex-Amor ◽  
Ignacio Parellada-Serrano ◽  
Francisco Gamiz ◽  
...  
Keyword(s):  
Wireless Communication ◽  
Communication Systems ◽  
Electromagnetic Waves ◽  
High Speed ◽  
Electromagnetic Response ◽  
Wireless Communication Systems ◽  
Full Wave ◽  
Communication Paradigm ◽  
Wireless Environment ◽  
Meta Atom

The upcoming high-speed wireless communication systems will be hosted by millimeter and sub-millimeter-wave frequency bands. At these frequencies, electromagnetic waves suffer from severe propagation losses and non-line-of-sight (NLOS) scenarios. A new wireless communication paradigm has arrived to resolve this situation through the use of reconfigurable intelligent surfaces (RIS). These metadevices are designed to reconfigure the wireless environment in a smart way. Traditional RIS designs based on the implementation of 2-D configurations have been considered up to now. However, 3-D structures enable an extra degree of freedom in the design that can be taken as an advantage for the development of improved RIS structures with advanced functionalities. This article proposes the implementation of a novel electronically-reconfigurable RIS based on the use of 3-D graphene meta-atoms. The reconfigurability lies on the graphene conductivity, easily tunable with a biasing voltage. Different conductivity values vary the meta-atom electromagnetic response, modifying the RIS functionality. A multi-objective optimization framework determines the optimal phase state of each meta-atom to accomplish the desired RIS performance. The operation of the RIS as an efficient beam steerer/splitter, absorber and polarization selector is validated with full-wave results.

Side-lobe Level Reduction of an Optical Phased Array Using Amplitude and Phase Modulation of Array Elements Based on Optically Injection-Locked Semiconductor Lasers

Photonics ◽  
2020 ◽  
Vol 7 (1) ◽  
pp. 20
Author(s):  
Anh Hang Nguyen ◽  
Jun-Hyung Cho ◽  
Ho-Jun Bae ◽  
Hyuk-Kee Sung
Keyword(s):  
Semiconductor Lasers ◽  
Power Efficiency ◽  
High Performance ◽  
Phased Array ◽  
Beam Steering ◽  
Side Lobe ◽  
Real Field ◽  
Side Lobe Level ◽  
Amplitude Profile ◽  
Optical Phased Array

The side-lobe level (SLL) in optical phased array (OPA) systems should be reduced to ensure their high performance. We investigate theoretically the performance of an OPA based on optically injection-locked (OIL) semiconductor lasers. The phase and amplitude of the OIL laser are modulated by controlling the injection-locking parameters to reduce the SLL as well as to achieve beam steering. We successfully achieved an SLL reduction of >16 dB when compared with the uniform amplitude profile based on the application of the Taylor window function profile to the injection-locked OPA elements. The reduced SLL and high power efficiency achieved in this study can expedite the use of OPA in real field applications, such as free-space communication, imaging, and light detection and ranging (LIDAR).

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